The present invention relates to a wind power motor of the type having radial vanes.
There is a need for inexpensive wind power motors, which are easy to install, for operating electric generators, which are to power small power consumers on locations where the public electric mains are not available, for example on smaller islands, in sparsely populated areas, in developing countries etc. The traditional type of wind power motors including a propeller and currently available on the market, however, is relatively expensive to use for producing electricity, because an expensive gearbox has to be arranged between the relatively slowly rotating propeller shaft and the electric generator. In addition, a sturdy tall framework has to be provided capable of supporting the gearbox and the generator, which are usually mounted at top of the framework to avoid long power reducing transmissions.
A wind power motor of the type having radial vanes is disclosed in U.S. Pat. No. 4,086,026.
An object of the present invention is to provide a new wind power motor of the radial vane type, which is inexpensive, easy to install, has a high efficiency and is capable of directly operating an electric generator of standard type without need for any intermediary gearbox.
Accordingly, the present invention provides a wind power motor comprising a framework; a substantially horizontal rotor shaft journalled on the framework; a rotationally symmetrical rotor drum having a circumferential direction and rigidly connected to the rotor shaft coaxially with the latter, the rotor drum having a circumferential drum wall forming an open air inlet end and an open air outlet end, the drum wall having a wing profile-like axial cross-section, with the drum wall thicker at the air inlet end than at the air outlet end; and at least one vane attached to the rotor drum and having a front end and a rear end, which is displaced in the circumferential direction of the rotor drum relative to the front end. The vane acts on the rotor drum with a torque about the rotor shaft when wind is blowing against the air inlet end of the drum wall and hits the vane. This wing profile-like drum wall is aerodynamically beneficial, which results in a low air resistance at the air outlet end of the rotor drum, so that the wind power motor of the invention will have a high efficiency. That is the efficiency is increased compared to if a wing profile-like drum wall were not provided.
According to a preferred embodiment of the invention each vane comprises a straight front portion extending from the front end of the vane substantially axially along the rotor drum, and a curved rear portion curving from the straight portion to the rear end of the vane. This results in the advantage that power reducing air turbulence between adjacent vanes is substantially avoided. The displacement in the circumferential direction of the rotor drum between the front and the rear end of at least one of the vanes may advantageously be adjustable, so that the attack angle of the vane against the wind can be adjusted to the prevailing wind force. The adjustment of the vane to the wind force may suitably be achieved by adjusting the rear end of the vane in the circumferential direction of the rotor drum.
In accordance with another embodiment of the invention, the wind power motor comprises a tubular further rotor shaft coaxially journalled on the rotor shaft, a further rotationally symmetrical rotor drum, which is smaller than and arranged within the rotor drum and which is rigidly connected to the further rotor shaft coaxially with the latter, and a plurality of further vanes attached to the smaller rotor drum. Each further vane has a front end and a rear end, which is displaced in the circumferential direction of the smaller rotor drum relative to the front end of the larger rotor drum. Since the smaller rotor drum has a shorter diameter than the larger rotor drum it requires a relatively small torque for its rotation, which makes it suitable to utilize for relatively weak winds. Hereby, the wind power motor may be operated by relatively strong as well as relatively weak winds.
In principal, the further vanes on the further smaller rotor drum may be designed like the vanes on the larger rotor drum. However, preferably at least one of the further vanes extends radially out from the smaller rotor drum and axially along a portion of the latter, and at least one of the vanes extends radially from the larger rotor drum into the latter and axially along another portion of the smaller rotor drum, the last mentioned vanes of the two rotor drums radially overlapping each other.